I hoot as a result of a sneeze (7)
I believe the answer is:
atishoo
'a sneeze' is the definition.
(I've seen this before)
'i hoot as a result of' is the wordplay.
'a result of' is an anagram indicator.
'i'+'hoot'+'as'='ihootas'
'ihootas' is an anagram of 'ATISHOO'.
(Other definitions for atishoo that I've seen before include "report of involuntary escape from trap?" , "25 sound" , "Sudden eruption" , "Word to be sneezed at" , "Sound of a sneeze" .)